<div>
  <div style="font-size: 60px;">{{count()}}</div>
  <button (click)="set()">set</button>
  <button (click)="add()">+1</button>
  <button (click)="del()">-1</button>
  <div>{{ count() }}</div>
  <button (click)="plus()">plus</button>

  <button (click)="toggle()">toggle</button>
  @if(cond()) {
  <div>This is A</div>
  } @else {
  <div>This is else</div>
  }
    单价<input type="number" [(ngModel)]="params.price" (ngModelChange)="changePrice($event)"/>
    数量<input type="number"  [(ngModel)]="params.num" (ngModelChange)="changeNum($event)"/>
    总价：{{totalPrice()}}
</div>
